Various methods and apparatuses are already known for determining the exact position of a target by using a source of radiation emitting radiation which can be received by a receiver device, the said source and said receiver device being disposed on opposite sides of said target (see EP-A-0 242 565 or EP-A-0 260 550).
In prior apparatuses, the source of radiation is exclusively a source of X-rays, thereby tending to subject a patient to considerable doses of X-ray irradiation, which is not desirable.
Further, prior methods and apparatuses require the X-ray source and the radiation receiver device to be fully integrated with equipment for treating the target, which means that radiation sources that may already exist in treatment centers are unsuitable, thereby considerably increasing the cost of such apparatuses.
Another major drawback of prior methods and apparatuses lies in the fact that they require the initial position of the source to be known, which is why they need to be fully integrated in the target treatment equipment.
Thus a main object of the present invention is to solve the novel technical problem consisting in determining the exact position of a target independently of a priori knowledge of the position in three dimensions of the source of radiation.
Another main object of the present invention is to solve the novel technical problem consisting in providing a method and an apparatus for determining the exact position of a target without a priori knowledge of the distance and/or angular position in three dimensions of the source of radiation relative to said target, the apparatus being simple in design and cheap.
Another object of the present invention is to solve the novel technical problem consisting in providing a method and apparatus for determining the exact position of a target independently of a priori knowledge of the position in three dimensions of the source of radiation making use of a source of radiation which is independent of the target treatment equipment, which is particularly advantageous for therapeutic treatment of targets that may be constituted, for example, by cells, lithiases or concretions, or bones to be treated. The invention also makes it possible to use sources of radiation that are available in treatment centers for other purposes.
Another object of the present invention is to solve the novel technical problems specified above with a minimum of manipulation, in particular using a minimum number of steps or taking a minimum number of pictures with the localization apparatus, thus limiting the dose of exposure to the radiation emitted by the localization apparatus, which is particularly important when the localization apparatus emits X-rays.
Another object of the present invention is to solve the novel technical problem consisting in determining the exact position of a target without having to displace the patient.
For the first time, the present invention makes it possible to solve the technical problems specified above simultaneously, particularly simply, cheaply, and in a manner
that is usable on an industrial scale.